Just wondering, because I can't find anything...

There is, to my knowledge, only one book on Category III cinema and it's in French and long out-of-print (so is going for quite a bit over the RRP which was €55 to start with, I may try an interlibrary loan at some point):

Sévéon, Julien (2009) Category III: Sexe, sang et politique à Hong Kong. Bazaar & Co (ISBN 9782917339039)

Press release:

Translation:

SEX, BLOOD AND POLITICS IN HONG KONG BY JULIEN SÉVÉON

Category III: Hong Kong classification equivalent to the ban on under-18s.

In 1988, after a mini scandal in the world of cinema, a new film classification system appeared in Hong Kong whose aim was to allow the local distribution of foreign works with subject matter and/or content deemed tendentious (politics, art and essay...). The most "risky" films are then distributed under the Category III label, which effectively allows a number of productions, which would not otherwise have been able to be screened, to see a release.

Category Ill quickly obtained unexpected results with the launch of hundreds of local productions with sex and violence as their motto. While the countdown to 1997 and the return of Hong Kong to China echoes painfully in the heads of all the inhabitants, Category III allows the British colony to torture its minds... with massacres, black magic and all-out sex!

Category III, Sex, Blood and Politics in Hong Kong is the first book in the world to look into this phenomenon, the most important in Hong Kong cinema from the end of the 20th century, but, paradoxically, the most misunderstood.

From key films and recurring themes, the author dives into the darkest streets of Hong Kong (or even China) and paints an unexpected portrait of the city and its cinema. Supported by around ten interviews with directors and actors most intimately linked to this trend, this book also gives pride of place to a rare and unpublished iconography.

The author, Julien Sévéon

Passionate about cinema and particularly its most obscure and strange aspects, Julien Sévéon writes in the French press (Mod Movies, Kumite, Animeland...) and English-speaking (Asian Cult Cinema, Dark Side...) and regularly speaks on DVD supplements. He was editor of Mad Asia, as well as Grindhouse and Cinemas of Asia special issues. He is also the author of the books Le Cinéma enragé au Japon and Blaxploitation, 70's Soul Fever (also available from Bazaar & Co).

However, there are other useful books and I'll drop them into the comments and update the list here.

Academic papers (previously mentioned) include:

• Davis, Darrell W. & Yeh, Yueh Yu (2001) "Warning! Category III: The other Hong Kong cinema." Film Quarterly 54 (4): 12-26
• Woods, Allen (2001) "Category III Films and VCDs: The Failure of Deterrence in the Copyright Ordinance of Hong Kong." Vanderbilt Journal of Transnational Law 36 (3): 1073-1112.

Abstract:

In 1997, the government of Hong Kong enacted the Copyright Ordinance. The goal of the Ordinance was to establish a strong deterrent against the illegal manufacture and sale of copyright infringing materials, especially pirated video and digital compact discs. Courts have interpreted the Ordinance to allow the Customs and Excise Department sweeping powers of search and seizure. As a result, the government has seized many thousands of copyright infringing video compact discs and courts have enforced lengthy custodial sentences against guilty parties.

Despite these efforts, though, film piracy continues to grow throughout Hong Kong and transnational film interests have begun to call for even more stiff penalties and greater deterrence. The failure of the current deterrent in the Ordinance, however, suggests that continuing with that approach to combat piracy will most likely fail. As a result, this Note examines the many cultural and legal issues surrounding the supply and demand for copyright infringing discs and argues that Hong Kong must take a different approach, not relying on deterrence, to resolve this growing problem.

Reference:

• Woods, Allen (2001) "Category III Films and VCDs: The Failure of Deterrence in the Copyright Ordinance of Hong Kong." Vanderbilt Journal of Transnational Law 36 (3): 1073-1112.

Includes a link to download the PDF.

The human faces of the Category III film were often female. Actresses' bodies and expressions were used not only on official—and therefore government-approved—advertising but also regularly featured in the mainland Chinese tabloid papers, in detailed lists of Category III movie highlights, right down to VCD time codes. Some Hong Kong actresses understandably did not enjoy being defined by their producers' grubby demands, but some women became stars of the accommodating umbrella genre anyway.

This is the last of a series on Fangoria but their own links don't work so I am bringing them together here:

A Guide To Hong Kong Category III Shockers:

• Ghosts, Black Magic, And The Supernatural
• EBOLA SYNDROME Star Anthony Wong Haunts Your Dreams
• Terrors Ripped From The Headlines
• The Many Faces of DR. LAMB Star Simon Yam
• Sexual Violence
• Leading Ladies

Riki-Oh, a young man who has superhuman strength, is incarcerated in a private prison, where inmates are treated like slaves. He is forced to use his unstoppable form of martial arts to destroy the corrupt officials and their lackeys.

IMDb

Availability:

• Blu-ray from 88 Films
• Blu-ray from Mediumrare
• DVD from Hong Kong Legends
• DVD from Cine-Asia
• DVD from Tokyo Shock
• VHS from Media Blasters

Download available from the Internet Archive.

edit: should have been posted in home video - sorted and deleted this.

They are:

• Anaconda Collection - UK
• Ark of the Sun God 4k - UK
• Battle Creek Brawl (Deluxe Edition) - UK
• The Blue Jean Monster - UK, US
• Hell of the Living Dead - UK
• Hell of the Living Dead 4k - UK
• The Inspector Wears Skirts - UK, US
• Iron Warrior - UK
• Knock Off - UK?
• Magic Crystal - UK
• The Medallion - UK

This includes re-releases, represses and replacements.

Tech specs at Blu-ray.com

Blue Jean Monster release also posted about in the Category III community.

If you want to put the Category III on your clothing you can have a few options at Redbubble:

Redbubble:

• Big black triangle
• Smaller black yriangle
• Red triangle

Teepublic:

• Black triangle, no text
• Empty triangle, no text

Transparency: I am neither of the sellers but I have just bought the smaller black one and will be wearing it to see Enter The Dragon later.

A gang of unhappily subtitled detectives follow a trail of pilfered pituitary glands across Hong Kong, uncovering a coterie of black market habitues with equally desperate claims to illicitly harvested human growth hormones.

IMDb

Full movie

Someone messaged the author of the list the link below that might be more comprehensive.
http://www.hkcinemagic.com/en/imovie.asp?y=&alpha=&gid=15&s=0

Abstract:

This essay analyzes the workings of films classified as Category III in Hong Kong: pictures with explicit pornographic and "porno-violent" content that are restricted to adults only. We also consider Hong Kong's film ratings system in light of political censorship, artistic freedom, and the fortunes of the film industry in the post-1997 period. We note the preponderance of these films in Hong Kong, and see Category III as a microcosm of the industry rather than a reactionary exception. The rating functions as a marketing device to entice as well as warn, and more broadly to reassure the world of the continued existence of Hong Kong's freewheeling, permissive society. Category III films and their regulation reveal the tug-of-war between transgression and control throughout Hong Kong media.

Reference:

• Davis, Darrell W. & Yeh, Yueh Yu (2001) "Warning! Category III: The other Hong Kong cinema." Film Quarterly 54 (4): 12-26

The link is directly to a PDF of the paper.

The 1990s were a notorious period in the history Hong Kong cinema. By turns gory sexualised, violent and just plain outrageous, Category III films quickly gained a reputation as cult films. As often in extreme exploitation movies, these films challenged a whole range of societal norms and French critic Julien Sévéon will explore the taboo breaking aspects of Category III films that has made them such a cultish draw for so many. Examining films before and after the handover of Hong Kong to China, Dr Calum Waddell (University of Lincoln) will interrogate the ways in which these films seem to foreshadow the current political crisis in Hong Kong. We will also be joined by Dr Victor Fan(King’s College, London) who will turn his wide-ranging expertise in Chinese cinema and politics on to the crazy, bizarre and confrontational world of Category III.

A near retired inspector and his unit are willing to put down a crime boss at all costs while dealing with his replacement, who is getting in their way. Meanwhile, the crime boss sends his top henchmen to put an end to their dirty schemes.

IMDb

Availability:

• Full film on YouTube

Home video:

• Dragon Dynasty R1 Blu-ray
• Various German releases

 A cop turns into a monster after being gunned down and electrocuted in a Triad shootout.

Availability:

• DVD from Joy Sales Legendary Collection (sold out)

Full film on YouTube, download available on the Internet Archive

From 1988-1999, Category III titles made up 38-48% of theatrically released Hong Kong productions. (1) In 1992, Category III movies like Dr. Lamb and Naked Killer grossed a total of $159 million HKD ($43.8 million USD, after adjusting for inflation); in 1993, movies like Daughter of Darkness and Run and Kill added $185 million HKD ($46.5 USD today). (2) Category III ratings weren't just for impotent serial killers and horny ghosts—movies about triad gangsters or anybody that threatened diplomatic relations with mainland China were also either taboo or subject to censorship.

Category III movies were a symptomatic last gasp for independent Hong Kong films, whose popularity had been waning for about a decade or more thanks to the rise of Cantonese-language TV programming and the burgeoning bootleg VCD market.

This is the first of a series on Fangoria but their own links don't work so I am bringing them together here:

A Guide To Hong Kong Category III Shockers:

• Ghosts, Black Magic, And The Supernatural
• EBOLA SYNDROME Star Anthony Wong Haunts Your Dreams
• Terrors Ripped From The Headlines
• The Many Faces of DR. LAMB Star Simon Yam
• Sexual Violence
• Leading Ladies

When rotted human remains wash up on a beach, the police are dispatched to investigate. Their searching leads them to the Eight Immortals Restaurant, with it's local proprietor Wong Chi Hang is the man behind it. But it seems Wong has ownership of the restaurant without proof, which leads one cop, above all his bumbling peers, to think there's more to Wong than he's willing to tell. As their investigation progresses, the cops find themselves on a missing persons case when the man who originally ran the restaurant and his entire family have just gone missing without a trace. The only man with knowledge of what happened to that family is Wong, who very well may be responsible for the disappearances of employees too, and what the cops must find, will be an unlikely horror they couldn't anticipate, of a far more dangerous man capable of doing even more evil acts, in the one thing no one had even thought about.

Full movie (turn on subtitles)

Blu-ray available from 88 Films (Deluxe Edition)

An evil wizard uses his powers to make women vomit live centipedes to eat them.

Full movie

Blu-ray available from Error 4444.

from this, some of the gnarliest horror movies ever made came from this system, and some were so abhorrent they were retroactively added to Category III. So today we're going to take a look at twelve very memorable Category III Hong Kong horror movies.

Excellent overview.

The link is to part 1 and here's part two.

edit: fixed link

cross-posted from: https://feddit.uk/post/601310

One of the most infamous movies branded with Hong Kong's 'adults only' Category III rating, Taxi Hunter bravely tackles the under-explored scourge of – er – unprofessional taxi drivers. After his pregnant wife is perishes through the actions of a careless (and callous) cabby, mild-mannered Ah Kin (Anthony 'king of the Cat III's' Wong) declares war on the entire profession – and you don't need 'The Knowledge' to know he won't be leaving a tip...

Directed by Herman Yau (who unleashed Ebola Syndrome on an unsuspecting world) 88 Films are pleased to present this important treatise on public transport in a wonderful new blu-ray edition

A good introductory article.

Welcome